Why dosen’t NASA use jet boosters on rockets? I figure, a few
disposable or reuseable turbo/ramjets (like that on the SR-72
Blackbird) on the main stage…employed during the trans-atmospheric period of the launch would save the weight and internal volume of carrying your own oxygen.
Would the thrust to weight ratio be impractical?
Perhaps running an oxygen line directly to the jets’ combustion
chambers?
Jet engines are expensive. Even floating them back to earth under a parachute is likely to damage them. If they land in the sea salt water can’t be too good for them and dropping them onto the ground would likely cause all sorts of damage. Merely reparing them and tuning them up for another flight would likely be costly and not worth the effort. Solid rocket boosters are probably simpler to deal with in this fashion.
Additionally, for flat out thrust a jet can’t really compare to a rocket. A jet engine that would rival the thrust of the solid rockets on the shuttle would likely have to be huge and impractical.
Not to mention that the flight profile of a ballistic rocket makes using a jet impractical. Because a rocket accelerates continuously, the time that it spends in a useful speed range for a jet engine would be very short. It just wouldn’t be worth the effort.
However, Orbital Science Corporation uses a jet aircraft (a Lockheed L-1011) as a “first stage” carrier for its Pegasus rocket. The rocket is carried underneath the aircraft and released at about 40,000 ft. It can put up to 1000 lb into low-Earth orbit.
[nitpick] - it was probably a tpyo, but there is no “SR-72 Blackbird”. It’s the SR-71.
Ditto on jet engines not being nearly as powerful as rockets of comparable weight. There’s also the factor of the thousands of moving parts in a jet engine vs the minimal number of moving parts in a rocket engine. This is a big factor when your engine is all that keeps you from hitting the ground.
Many heavy aircraft used by the military such as tankers use rockets to assist the jet engines. It was one of these rockets that was part of the urban legend about the guy that strapped the JAT rocket to his Chevy and flew himself and the car into the side of a cliff.
Yup…here’s a picture of a C-130 using one.
Called a JATO not a JAT I believe (Jet Assisted Take-Off)
I heard about that myth. First read about it in Car and Driver…
or is it Motor Trend?
Anyways…
A few years ago, the police out in the mid-west notices some
wreckage at the base of a cliff. Seeing how flattened the sheetmetal was, they knew the impact was several hundred miles per hour, so they naturally assumed it was an aircraft.
Upon closer inspection, it turned out to be an Impala SS.
Apparently, some guy got one of these JATO bottles and attached
it to his Hot-Rod, found a long straight stretch of road to ride,
and let 'er rip.
Onlya bend in the road up ahead neccesitated decelleration…
impossible until the fuel in the JATO is fully expended.
The poor sap burned out his brakes, still going 300+ MPH upon
impact.
Or so the story goes.
Snopes says it never happened.
If this guy is on the level, there may be some truth behind the Rocket Car urban legend. The story he tells is much more believable than the urban legend, so I lend it at least a little bit of credence.
